1. Field of the Invention
The present invention relates to a smart keyless entry system for unlocking the doors of a vehicle based on mutual authentication between a portable unit and a vehicle-mounted unit (vehicular controller) when an user of the portable unit touches an outer handle of the vehicle which functions as a touch sensor, or a vehicular door lock remote control apparatus for unlocking the doors of a vehicle in response to a key operation on a keyless transponder.
2. Description of the Related Art
Recently, various vehicular door lock remote control apparatus have been proposed for remotely locking and unlocking the doors of a vehicle with a portable unit that is capable of sending and receiving a radio signal.
For example, according to the first arrangement of Japanese laid-open patent publication No. 60-159259, there is disclosed a smart entry system in which the vehicle transmits a request signal when a door switch on an outer side of a vehicle is operated, and when a normal response signal is received from a portable unit, the doors of the vehicle are unlocked based on the result of a mutual authentication process.
According to the first arrangement, during a certain period of time after the doors are locked, the vehicle does not transmit a request signal unless the portable unit is present in a reception range near the vehicle. Therefore, even when the door switch is tampered with, a request signal will not be transmitted from the vehicle.
According to the second arrangement of Japanese laid-open patent publication No. 11-141211, a smart entry system based on mutual authentication without button operations is adopted in combination with a keyless entry system based on unidirectional authentication from a portable unit to a vehicle using button operations. When the smart entry system and the keyless entry system conflict with each other, priority is given to the keyless entry system.
Other systems for locking doors that have been conventionally available in the art include a keyless lock system for operating a door lock knob switch to lock the doors while the doors are open, and a key-lock system for locking the doors with an ignition key.
According to the third arrangement of Japanese laid-open patent publication No. 10-176448, since the user of a smart entry system tends to try the door handle for confirming that the door is locked immediately after locking the door, a timer prevents the smart entry system from being actuated by the operation of the door handle which unlocks the door, for a predetermined period of time immediately after the door is locked.
With the first arrangement which inhibits a request signal from being transmitted for a given period of time, when the door handle is operated after the door is locked by another locking process, the vehicle transmits a request signal and the door is unlocked. Therefore, it is impossible to confirm that the door is actually locked.
With the second arrangement, if the door handle is operated during operation of the keyless lock system, a request signal is transmitted and the door is unlocked, making it impossible to perform keyless locking on the doors.
With the third arrangement, the predetermined period is set to 2 seconds or longer. However, it is difficult to set the predetermined period because the time required to confirm the locking of the door differs from user to user.